The Clinical Outcomes Core plays a central role in the proposed center, and will interact with several of the Cores (see Figure 1). The Core is justified by the recognized need to develop new outcome measures for HIVassociated cognitive disorders in the era of highly active antiretroviral therapy (HAART) that are not only robust and well validated, but also sensitive to changes that are expected earlier in the development of HIVassociated cognitive impairment. Also, the statistical power of recent trials for HIV dementia has been limited by excessive variance in the scores of standard neuropsychological test batteries (1). There is currently no funding venue for the kind of outcome measure development proposed in this Core. The individual responsibilities of key personnel are detailed in the Budget Justification. In brief, Dr. Ned Sacktor will direct this Core and oversee the collection of clinical data including neurological assessments. Dr. Ola Seines will oversee the collection of neuropsychological data and assist Dr. Sacktor in subject characterization. Dr. Scott Zeger, Richard Skolasky, and Dr. Kelly Gebo will collaborate with them on the design, data collection and management, statistical analyses, and interpretation of the performance characteristics of the instruments. Dr. Richard Moore, a recognized expert in the development of touch-screen testing devices will supervise these aspects of the Core.